[Galanwe]

What would automatic discovery even do? Add you to some worldwide IP overlay on top of internet? What would be the use of that?

I did had a use case in the past for peer to peer VPNs, mainly because in the 2000s, most hosting companies would only provide you crappy VMs with a single public interface. If you needed some control over the network, subnets, etc, then you would need some kind of overlay. This, added with the fact that you would typically have dozens of heterogeneous boxes at different providers, made maintaining a traditional host to host ipsec full mesh nightmarish. I used n2n (a peer to peer VPN) to reconciliate these various internet facing boxes in a single private IP network.

Nowadays, cloud providers are much more evolved, and offer you full configuration of multiple public/private interfaces, so recreating subnets over public facing boxes is not really a concern, which is why IMHO peer to peer VPNs do not serve much purpose in 2021.

[mynameisvlad]

https://tailscale.com for instance will show all the peers on the network in the menu bar of the app.